This invention relates to improvements in systems for generating and dispensing ozone. In particular it relates to improvements in the electrical and physical designs of those ozone generating systems which generate ozone from air or oxygen using high voltage electric fields.
For nearly twenty years corona discharge ozonators have been available from manufacturers including the Kerag Company of Switzerland, Welsbach, Union Carbide, Sauter, Degrement, Trailigaz and others. The Kerag system is typical of many of these and is one of the best known corona discharge ozonating systems.
In the Kerag systems air is sucked in, and it is then drawn (again by suction) through silica gel in order to dry it, and then through various types of filters (in which airborne particles are removed) in order to purify it. The oxygen in the air is converted into ozone by a corona discharge; finally, the generated ozone is sucked into an electrically operated mechanical dispenser which ejects it into the surrounding atmosphere (normally contaminated air or liquid). The structure and operation of the Kerag system is described in Kerag Brochure of 1976 entitled "Ozonized Water=Hygienic Water" which is herein incorporated by reference.
In the Kerag systems, the ozone generation occurs in what is known as an ozone generating cell. The cell is a large drum with a metallic disc at the top. Glass cylindrically shaped tubes, which, are, however, closed at the lower end, are held in the drum and extend from the bottom of the drum nearly to the top; a hollow metallic electrical conductor inside each glass tube makes contact through a high voltage fuse with the disc at the top of the drum and extends from the top of the glass tube downward to almost the bottom of the tube. The drum contains water which surrounds the glass tubes along most of their vertical lengths. The upper portions of the inner metallic tubes are open to allow the inward passage of air. Outward passage of ozone also occurs through the open tops of the glass tubes. Electrical current is fed through the metal disc at the top of the drum through the fuses and then to the metallic inner electrodes thereby producing a corona discharge between the outer surface of the inner metallic tube and the inner surface of the glass tube. When air or oxygen is sucked into the glass tubes ozone is thus produced and then is sucked out of the tubes and to the point of dispersion. Thus, it is clear that the principal phenomenon effected in the Kerag ozonator system is electrical--it is the production of ozone from air or oxygen by corona discharge in the glass tubes of the ozonator cell.
However, some of the other major components of the Kerag system are electrical as well. The Kerag disperser includes a mechanical mixer with a rotatable shaft which is driven by an electric motor. In addition there is an electrically driven heater and blower sub-system in the system. Before any ozone production takes place, air is drawn into the system and is passed through a tank of dried silica gel material; the silica gel removes moisture from the air. This provides for more efficient conversion of oxygen to ozone and prevents the undesirable formation of nitric acid. However, eventually, the silica gel becomes saturated with moisture and is no longer effective in absorbing water from the air. The silica gel tanks are therefore equipped with heaters and blowers which provide heat to the silica gel which dry it and make it suitable for continued use as a moisture absorbant. The regeneration heater and blower in the Kerag systems is electrically operated.
Thus, it is apparent that several components of an ozone generating system are usually electrical and that the electrical loads imposed in such a system by these components vary significantly. The ozonator cell in which the corona discharge occurs constitutes a heavy electrical load. The disperser which operates whenever the ozonator cell is operated constitutes a much lighter electrical load. The heater and blower systems also constitute relatively light electrical loads.
Normally, all of the electrical components of the Kerag type system are driven by three phase a-c power provided by a local power company. In other cases, an auxiliary three phase power unit is utilized. Those skilled in the art are well aware that it is good engineering practice to provide a balanced electrical load throughout an electrical system, thereby assuring uniform power and voltage levels for each power phase in the system. It has been recognized that this can be done in an ozonator system such as the Kerag system, theoretically, by connecting a three phase transformer to the three phase electrical supply so as to provide three phase power to the ozonator cell, the heaviest electrical load component in the system. However, formidable practical obstacles have, prior to this invention, prevented the development of such a balanced load ozonator system.
Accordingly, in the Kerag systems a single phase transformer is connected across one phase of the three phase electrical supply and supplies single phase power to the ozonator cell. Thus, for most of the time that such a system is operated, the electrical load is unbalanced because the single phase transformer connected to the ozonator cell constitutes a very heavy electrical load on one phase as compared to the relatively light electrical loads on the other two phases of the electrical supply.
One factor preventing the development of an ozone generating system operating with a balanced electrical load, was the art's manifested belief that a balanced load system was more costly than the unbalanced system. It was believed that the balanced load system, in which the ozonator cell is driven by three phase power, would require separate electrical control equipment for each power phase. Thus, it was thought, that to control the voltage in a single ozonator cell, three control systems would be required. Naturally, this would have involved considerable additional expense.
A second factor preventing the development of a balanced three phase power system was the perceived danger. It was believed that it was not possible to provide adequate insulation in an ozonator cell operated on three phase electrical power which would prevent leakage and arcing.
Efforts have been made in the art to develop an ozonator cell capable of being operated with three phase power. However, prior to the present invention all efforts were unsuccessful.
It is an object of the present invention to provide a balanced electrical load ozone generating system.
It is a particular object of this invention to provide an improvement over systems of the Kerag type by providing a partitioned ozonator cell which can be driven by three phase power. It is a further object of the present invention to overcome the problems which have heretofore prevented the development of a balanced electrical load ozonator system and to provide a safe and efficient, properly insulated, partitioned ozonator cell capable of being driven by three phase power at a reasonable cost.
It is a further object of this invention to provide a novel electrical control system for controlling the electrical operation of a three phase power ozone generating system.